Magnetic compass



Nov. 27, 1945.

A. A. STUART, JR

MAGNETIC COMPASS Original Filed May 21, 1940 3 Sheets-Sheet 1 INVENTOR g /ffed Al'fiuar/l J j ATTORNEY.

Nov. 27, 1945. A. A. STUART, .n

MAGNET]: C COMPAS 5 Original Filed May 21, 1940 -3 Sheets-Sheet 2 lNV ENTOR. g/Fred A. Sfua'rlfiJr: /W$Wm, ATTORNEY.

Nov; 27, 1945 v A. A 'STUART, JR 1 R 22 Q MAGNETIC COMPASS Original Filed May 21, 1940 s Sheets-Sheet s g (h z:

INVENTOR. /f'red A Sfuqrf; Jr, 9 J%W.

I ATTORNEY..

Reiuued Nov. 27, 1945 UNITED STATES PATENT OFFICE MAGNETIC COIHPASS Alfred A. Stuart, Jr., Hasbrouck Heights, N. 1., assignor to Bendix Aviation Corporation, Teterboro, N. J a corporation of Delaware 7 19 Claims. The present invention relates to magnetic compasses, and more particularly to the so-called earth inductor type of compass, and is a continuation of application Serial No. 336,444, filed May 21, 1940, entitled Magnetic compass, which is, in turn, a continuation in part of application Serial No. 248,344, filed December 29, 1938, now Patent No. 2,240,680, dated May 6, 19 entitled Earthinductor compass."

Compasses used in navigation, and particularly in navigation of aircraft, have several disadvantages, chief among which are their insensitivity and their undependability during pitch and roll and under the effects of accelerations usually encountered on shipboard and in aircraft, and the fact that most earth inductor compasses of the prior art type required the rotation of the earth inductor element for generating the required voltage or for follow-up purposes.

The present invention has for one of its obj ects Application for reissue of a magnetic needle or other magnetic element.

The foregoing and other objects and advantages of the invention will appear more fully-hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein two embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for illustration purposes only, and are not to be construed as defining the limits of the invention, reference being had for this purpose to the appended claims.

In the drawings, wherein like reference numerals refer to like parts in the three embodiments:

.Fig. l is a partly schematic representation of a magnetic compass of the present invention;

Fig. 2 is a showing of an essential part of the present invention which may be substituted in the provision of a novel structure for overcoming the foregoing and other deficiencies in magnetic compasses of the prior art, especially in prior earth inductor compasses, as will appear more fully hereinafter.

Another object of the present invention is the provision of an improved magnetic compass of the earth inductor type in which the earth inductor element'is relatively stationary and has no rotatable or moving parts and is supportedon the ship or aircraft in a fixed reference plane by a stabilizing gyroscope, as distinguished from the earth inductor compass disclosed in the aforesaid Patent No. 2,240,680 in,which the earth inductor includes a rotatable element requiring an electric motor to rotate it in order to generate the required electromotive force from the earths magnetic field, thereby making it diflficult to employ a stabilizing gyroscope to maintain the inductor in a fixed reference plane.

A further object is to provide an improved magnetic compass of the earth inductor-type disclosed in the aforesaid Patent No. 2,240,680, but in which the only rotating parts are in the remote indicator,

thereby eliminating the necessity of using an electric motor or other prime mover to rotate the earth inductor or any part thereof, and making it possible to readily stabilize the inductor in a fixed reference plane by means of a stabilizing gyroscope of gyro-vertical.

Still another object is to provide a novel and improved magnetic compass, the indications of which may be amplified by a torque amplifier, and also to provide a magnetic repeating device which will repeat, with amplified torque, the movement Fig. 3 is a showing, partly schematic, of the earth inductor compass stabilized in horizontal plane by a gyroscope;

Fig. 4 a schematic illustration of the compass shown in Fig. 1 with a slight change in the circuit thereof.

Briefly, the present invention, instead of having a rotatable earth inductor as in Patent No. 2,240,680, includes a novel pick-up device of material having high permeability and low retentivity, which is relatively stationary and which has a portion periodically magnetically saturated and unsaturated, and another portion having windings connected in multipolar relation, in which are induced voltages, the relative values of which are representative of the angular relation between a selected axis of symmetry of the pickup device and the direction of the earths magnetic field. These voltages are conducted to a remote receiving device which may be an Autosyn," in the rotor of which are induced voltages similar to those induced in the windings oi the relatively stationary pick-up device. An indicating pointer connected to the rotor will, therefore, indicate the direction of the earths magnetic field, or the angular displacement of the pick-up device in the earth's magnetic field with the craft on which it is mounted. By means of an amplifier, the torque of the rotor may be increased to any desired value.

Having particular reference to Fig. 1, I0 designates a relatively stationary and non-rotatable magnetic pick-up device of highly permeable material, such as Permalloy" or "Mumetal, having legs ll, l2 and I3, symmetrically disposed degrees apart and converging upon the central ring portion, or stationary armature I 4, of the same material. The legs II, I2 and I3 have windings I5, I6 and I1, respectively, wound thereon, and central portion I4 has an exciting winding I8 which may be split up as shown, into three equal portions for the purposes of symmetry. Winding .I3 is connected through leads I3 and 23 to a source of alternating current 2|. Windings l5, I6 and I1 have their inner ends connected to ground, and their outer ends 22, 23 and 24, respectively, are connected to coils 25, 26 and 21, respectively, which are wound about the. poles of the stator 23, of a conventional Autosyn" motor 23. Rotor 33 of Autosyn 29 carries a coil 3|, which is connected through leads 32 and 33 to the input of vacuum tube amplifier 34. The output of amplifier 34 is connected through leads 35 and 36 to one phase 31 of a two-phase induction motor 33. The other phase 39 is energized'from source 2| through a frequency doubler 43 by way of conductors 4| and of any conventional electrical coupling arrangement, such as condenser 43 and resistor 44. A suitable frequency doubler 43 may be of any conventional type; for example, it may be patterned after the frequency doubler shown and described on pages 706 and 707 of Principles of Radio Communication" by Morecroft, 2nd edition Rotor 45 of motor 33 is geared to rotor 3v through any suitable train 46 connected to shaft 41, which has a pointer 43 rotatable therewith for indicating direction upon the compass card of azimuth scale 43. The circuit including amplifier 34, induction motor 33, gear train 46, etc., acts to amplify the torque available in rotor 30 and coil 3|, and will be described later.

Assuming that the relatively stationary earth inductor III is disposed in the earths magnetic field in a horizontal plane and leg I I parallel with north and south, as shown in Fig. 1, with no exciting current in winding I 3, the earths field will thread through leg II and equally through legs I2 and I3, through armature I 4. As long as the flux in legs I I, I2 and I3 is in a steady state, no voltage will be induced in windings I5, I6 and I1. However, if sufficient excitation current is supplied to Winding I6 by source 2| to periodically saturate armature I4, then the earths flux will decrease in legs II, I2 and I3 at a rate depending upon the frequency of source 2|, and a voltage will be induced in each of windings I 5, I6 and I1, setting up therein, andin 00115 25, 26

and 21, an alternating current. windings I3, I3

and I1 are so situated on legs II, I2 and I3, respectively, that no'voltages are induced therein due to the saturation of armature I4. The magin the rotor gap of Autosyn 29, and the current in coil 3| due to frequency doubler 43 will set up' a field so that rotor 33 will be forced to rotate until the field of coil 3| is aligned with the refrequency doubler 40 and the voltage induced in windings I5, I6 and I1 by source 2|. Thus, pointor 43 carried by rotor 30 on shaft 41 will indicate netic field caused by saturation of armature I4 fiows only through portion I4 and does not enter legs I2 and I3. However, in saturating central armature portion I4, the reluctance of the path taken by the earths field in legs II, I2 and I3, prior to saturation, will become relatively high, forcing the earths field to decrease in armature I4 and legs II, I2 and I3, and to partially flow through a path of lower reluctance in the air.

While the torque amplifier described above is of decided advantage for certain uses of the'compass of the present invention, there is shown in Fig. 4 a circuit which does not employ a torque amplifier, but which is otherwise identical to the the true angular disposition of pick-up device II with respect to the earths magnetic field.

When the compass of the present invention is used to indicate extremely weak fields, such as the earths magnetic field, the use of the torque amplifier above described is desired, as extremely low torques resulting from current in coil 3 I acting in conjunction with the magnetic field resulting from the flow of currents in coils 25, 26 and '21, may be insufilcient to overcome the friction of the bearings and slip-rings attached to rotor 33. The current in coil 3| is amplified in the vacuum tube amplifier 34 and its output may be of any desired power rating without causing harmful reaction on coil 3|. It is a well-known characteristic of vacuum tubes that the output has no substantial reactive effect upon the input. Therefore, unless coil 3| is in a null position, phase 31 will be energized, thereby causing rotor 45 to turn gear train 46, shaft 41, and along with 8 the shaft, rotor member 30, until this latter member again reaches a null position, at which time phase 31 is de-energized and rotation of rotor 45 thereby stopped.

The winding 33 of one phase of rotor 33 is continuously energized from source 2| and through frequency doubler 43. No self-rotation of rotor 45 is possible while the winding of only one phase is energized, thus pointe 43 will not be rotated until there is current in coil, 3| which is amplified in amplifier 34 for energizing phase 31, and this condition is fulfilled only when pick-up device I 3 is being rotated in the earths magnetic field. The current flowing in coil 3| and phase Winding 31 will always be in the correct phase with respect to that in phase winding 33 .to cause rotation in the correct direction. Thus, 180 degree ambiguity is eliminated. A torque amplifier, similar to that here disclosed, is disclosed in the aforesaid application Serial No. 248,344, filed December 29, 1938, now Patent No. 2,240,680, and assigned to the same assignee as the present invention.

Those versed in the art will readily comprehend that upon angular displacement of the pick-up device I3 clockwise with respect to the magnetic field by the angle 6, the voltages incircuit shown in Fig. 1. The leads 32 and 33 of coil 2| are connected directly to the outp'ut'of frequency doubler 44. The currents in coils 26..

26 and 21 will set up a resultant magneticfield the same angle of rotation. This duced in each of the legs II, I2 and I3 will be each angle of displacement of pick-up device I Ii in the earths field,"pointer 43 will move through v relation holds true regardless of the angle or the direction of displacement of pick-up device III.

thereof will be given at this time.

A slightly different earth inductor or pick-up member 50, as shown in Fig. 2, may be substituted for the pick-up member l in Fig. 1, by merely superimposing Fig. 2 upon the circuit of Fig. 1, so that lines A and B coincide with lines A and B, respectively, of Fig. 1. Then the ends 22, 23 and 24 of windings l5, l5 and i1 will be replaced by ends 22', 23' and 24 of windings II, l6'-and ll', respectively, and leads I! and ll of exciting winding l8 will be substituted for the leads l9 and 20 of exciting winding l8.

With Fig. 1 modified in this respect, the operation of the complete circuit is identical to the operation of the circuit above described with respect to Fig. l. and ii are connected directly together without the use of a ring, such as ll in Fig. 1. When current from source 2| flows through winding ll it will saturate each of the legs ll, i2 and II in the central armature area within the circle designated l4 and no saturating flux will flow through that portion of the legs about which are wound coils i5, i6 and II. It has proved to be an advantage in production to form the pick-up member as represented by 50 in Fig. 2, rather than as shown at M in Fig. 1, but it should be borne in mind that the operation of both memhers is essentially identical.

Although it is intended to use the circuit of Fig. 1 as an earth inductor compass, it may have other possible uses. However, when it is desired to use the'device of the present invention as an earth inductor compass, it is essential to its faithful operation that the earth inductor or pick-up member III (or Dick-up member ill, if this form is preferred) be maintained in a horizontal plane. To this end it is proposed to mount pick-up member III as shown in Fig. 3, upon a gyroscope 5|, which is stabilized in any conventional manner about its vertical axis. Since different means of stabilization of gyroscopes about the vertical axis are well-known. no description However, upon gyroscope casing 52, there are mounted upright members 53 to which is attached a horizontal plate of insulating material 54, which carries pick-up device l0 secured thereto by any However, leg members ll, I2"

. 3 each exciting cycle, the earth's field will again increase through legs II, I! and i3 and induce another half cycle of alternating current each time in windings IS, IS and i1. It will beapparent that with a given value of the horizontal component of the magnetic field, the voltage induoed in windings l5, l6 and I1 will vary with the frequency of alternation of source I I.

The voltage induced in these windings also depends upon the saturation characteristics of the material used for central ring portion II. In order to simplify the explanation of the invention above given, it has been stated that the earth inductor or pick-up device It is made of a high permeable material, such as Permalloy or Mumetal." A high permeability is not necessary for the successful operation of this device, and many of the common paramagnetio materials such as silicon steel and soft iron can be success- 1 fully used. However, it has been found that the knees of the saturation curves for Mumetal and "Permalloy have an exceedingly sharp, bend as contrasted with the gradual, smooth curves of other magnetic materials. By the useof a material having a sharp knee to its saturation curve, a much higher voltage can be induced, since the saturation with the same exciting voltage and current will take place in a much shorter interval. Since the voltage induced in windings IS, IS and i1 will depend to a great extent upon the rate at-whichthe earths flux is expelled from legs II, I! and l3,-it will be readily apparent that a decided advantage is obtained by the use of these metals having a sharp bend on their saturation a direct current bias of a value such that with suitable means. The ends of windings 22, 23 and 24 are connected to the poles of stator member 28in the same manner as shown in Fig. 1, and leads I! and 20 are also connected to source 01 alternatin current 2| in the manner shown in Fig. 1. Since the circuit of Fig. 3 is identical to the circuit-of Fig. 1, no further explanation thereof is felt necessary.

It will be readily understood that regardless of pitch, roll or other accelerations of a ship or aircraft, gyroscope 5| will be maintained stable about the true vertical and thus, earth inductor or pick-up device II) will be maintained horizontal, and magnetic errors, resulting in false indications of pointer 48, which would appear without stabilization of pick-up device H), are thereby absent from the system.

It has been stated above that upon saturation of the central ring portion ll, magnetic flux, which otherwise threads through legs ll, I2 and II, decreases due to the great increase in reluctance which results from the saturation of ring ll.

saturating value, which happens twice during,

the bias alone, armature portion I4 is saturated; then on every other half cycle of alternating current from source 2|, the bias will be overcome by the alternating current and the frequency in the output of windings l5, I6 and II will equal the frequency of source 2 i. This latter arrangement has proven to be beneficial where it is desired to work at extremely high frequencies of alternation, since the hysteresis loss is cut down and therefore, more output may be obtained from the windings l5, l6 and i! of pick-up device Ill.

The earth induction or pick-up devices shown at Ill and 50 have three legs, but the use of any desired number of legs, either separate or integral,

such as four, iscomprehended within the limits of the present invention. If four'legs are used, the angular separation maybe degrees, and the legs may be formed integrally or of two or four pieces of material arranged to form a cross.

While only two embodiments of the present invention have been shown in the drawings, it is to be understood that various changes may be made without departing from the scope of the present invention. For this reason, it is intended not to limit the invention by the description herein given as an example, but solely by the scope of the appended claims.

What is claimed is:

1. In combination, controlling means comprising an inductive device having a multipolar stator winding and a rotor winding in inductive relation with said stator winding, a two-phase alternating current driving motor connected to actuate the rotor winding of said inductive device, a source of alternating current connected to energize one phase of said driving motor, an induction device comprising a closed core of highly I permeable magnetic material having a plurality of pole pieces projecting therefrom adapted to receive a magnetic flux from. auni-directional magnetic field, a winding oneach of said pole pieces, said pole piece windings being connected in multipolar relation to the multipolar winding of said inductive device, a, single phase winding on said closed core and energized by said source of alternating current for varying the uni-directional flux in said pole pieces whereby another alternating current is induced in said pole piece 'windings, and means connecting the rotor winding of said inductive device to energize the other phase of said driving motor, whereby the latter rotates to actuate the rotor of said inductive device upon relative angular movement between said induction device and said uni-directional magnetic field.

2. In combination, controlling means comprising an inductive device having a multipolar stator winding and a rotor winding in inductive relation with said stator winding, a two-phase alternating current driving motor connected to tuate the rotor winding of said inductive device upon relative angular displacement of said direction responsive means in azimuth.

3. An earth inductor compass comprising, in combination with an indicator, an electromagnetic device connected to said indicator and comprising a rotor member and a stator member, one of said members having a multipolar winding, a two-phase driving motor drivably connected to the rotor member of said electromagnetic device, an earth inductor device comprising a closed core having three radially projecting pole pieces,

a winding on each pole piece, said pole piece windings being connected together in multipolar relation and each winding connected to a corresponding pole of the multipolar winding of the electromagnetic device, a winding on the closed core of said earth inductor device, and 'a source of alternating current connected to said winding of said inductor device and to one phase of said driving motor to supply current to the winding of said one phase of said driving motor out of phase with the current supplied to the last-, named winding of said inductor device, the winding of the other phase of said driving motor being connected to the winding of the rotor of said electromagnetic device, whereby displacement of the earth inductor device in azimuth produces an electromotive forcein the winding of the rotor member of said electromagnetic device.

- '4. In-combination, controlling means compris ing an inductive device having a stator winding and a rotor winding, one of said windings being polyphase and the other being single phase, a two-phase alternating current driving motor con-v nected to actuate the rotor winding of said inductive device and having a'winding in each phase, a source 01' periodically varying current connected to energize the winding of one phase of said driving motor, a magnetic induction device comprising a relatively stationary core of highly permeable magnetic material adapted to be traversed by a magnetic flux from a unidirectional magnetic field and having a poLvphase winding thereon, means connecting said induction device to said source of periodically varying current to vary the reluctance of said core whereby'another periodically varying current is generated in the polyphase winding of said core member by the magnetic flux traversing said core member, means connecting the polyphase winding of said induction'device to the polyphase winding of said inductive device, and means connecting the single phase winding of said inductive device to energize the winding of the other phase of said driving motor, whereby the latter rotates to actuate the rotor winding of said inductive device upon relative angular movement between the core of said induction device and said uni-directional magnetic field.

5. A magnetic compass comprising a magnetic pick-up device having a stationary core of permeable material to be disposed in a unis-directional magnetic field, a multipolar winding on 7 said pick-up device, an exciting winding on said pick-up device, a source of periodically varying current connected to said exciting winding 'ior periodically saturating said pick-up device to produce in said multipolar winding an altemating current from said uni-directional field, a twophase alternating current driving motor having a winding in each phase thereof, means connect v ing said source of periodically varying current to one phase winding of said motor for energization thereby, means including amplifying means connecting the multipolar winding of said pickup device to the other phase winding of said motor whereby, upon relative angular displacement between said pick-up device and said unidirectional field, said other phase winding becomes energized by the alternating current pro-, duced from said uni-directional field to cause said motor to rotate, and indicating means controlled by the rotation of said motor. 7 6. In combination, controlling means comprising a magnetic pick-up device of permeable ma terial having a relatively stationary core and adapted to be disposed in a, uni-directional magnetic field for relative angular displacement with respect thereto, amultipolar winding on saidpick-up device, an exciting windingon said pick. f, up device, a source of periodically .varying current connected to said exciting winding for peri-e odically varying the reluctance of said pick-up cally varying current to-one phase winding of said motor for energization'thereby. means including an amplifier connecting the multipolar winding of said pick-up device to the other phase v winding of said motor whereby, upon relative angular displacement between said pick-up device and said uni-directional field, said other hase winding becomes energized by the alternating current producedfrom said uni-directional field to cause said motor to rotate, and means actuated by said motor in accordance with the amount and direction or relative angu lar displacement between said pick-up device and said uni-directional field.

'1. In an earth inductorcompass, a gyro-vertical, an earth induction device comprising a relatively stationary core of permeable material stabilized in a horizontal plane by said gyrovertical and disposed to receive the horizontal component of the earths magnetic field, a multipolar winding on said core, an exciting winding on said core, a source of periodically varying current connected to said exciting winding for periodically varying the magnetic reluctance or said core to produce in said multipolar winding an alternating current from said horizontal component of the earths field, an inductive device having a rotor winding and a, stator winding in inductive relation with each other, indicating means connected to be actuated by said rotor winding, a two-phase alternating current driving motor connected to actuate the rotor winding of said inductive device, said motor having a winding in each phase thereof, means connecting the multpolar winding of said induction device to one winding of said inductive device, means connecting said source of periodically varying current to one phase winding of said motor, and means connecting the other winding of said inductive device to the other phase winding of said motor whereby, upon relative angular displacement of said induction device in azimuth with respect to the earths field, said other phase winding becomes energized to cause said motor to rotate and actuate the rotor winding of said inductive device, thereby actuating said indicating means to indicate the drection oi the earths ileld.

8. In combination, controlling means comprising an inductive device having a stator winding and a rotor winding, one of said windings being polyphase and the other being single phase, a twophase alternating current driving motor connected to actuate the rotor winding of said inductive device and having a winding in each phase, a source of periodically varying current connected to energize the winding of one phase of said driving motor, a magnetic induction device comprising a relatively stationary core of highly permeable magnetic material adapted to be traversed by a magnetic fiux from a uni-directional magnetic field and having a, polyphase winding thereon, means connecting said induction device to said source of periodically varying current to vary the reluctance of said core whereby another periodically varying current is generated in the polyphase winding of said core member by the magnetic fiux traversing said core member, means connecting the polyphase winding of said induction device to the polyphase winding of aid inductive device, means connecting the single phase windin of said inductive device to energize the winding of the other phase of said driving motor, whereby the latter rotates to actuate the rotor winding of said inductive device upon relative angular movement between the core or said induction device and said uni-- directional magnetic field, and a gyro-vertical having said induction device mounted thereon for stabilizing said device in the horizontal plane.

9. In combination, controlling means comprising a magnetic pick-up device of permeable material having a relatively stationary, core and adapted to be disposed in a uni-directional ma netic field for relative angular displacement with respect thereto, a multipolar winding on said pick- 5 up device, an exciting winding on said pick-up device, a source of periodically varying current connected to said exciting winding for periodically varying the reluctance of said pick-up device to produce in said multipolar winding an alternating current from said uni-directional magnetic field, a two-phase alternating current driving motor having a winding in each phase thereof, means connecting said source of periodically varying current to one phase winding of said motor for energization thereby, means including an amplifier connecting the multipolar winding of said pick-up device to the other phase winding of said motor whereby, upon relative angular displacement between said pick-up device and said uni-directional field, said other phase winding becomes energized by the alternating current produced from said uni-directional field to cause said motor to rotate, means actuated by said m0- tor in accordance with the amount and direction of relative angular displacement between said pick-up device and said uni-directional field, and

a gyro-vertical having said magnetic pick-up device mounted thereon for stabilizing said device in the horizontal plane.

10. In combination, controlling means comprising an inductive device having a multipolar stator winding and a rotor winding in inductive relation with said stator winding, a two-phase alternating current driving motor connected to actuate the rotor winding of said inductive device, a source of alternating current having a predetermined frequency, a frequency doubler connected to said source for doubling the irequency of the current from said source, means connecting said frequency doubler to energize one phase of said driving motor by said double frequency current, direction responsive means comprising an induction device including a multipolar-winding connected to thmultipolar winding of said inductive device and a single phase winding energized by said source of alternating current whereby another alternating current is generated in the multipolar winding of said induction device, having the same frequency as the double'frequency current from said frequency doubler; and means connecting the rotor winding of said inductive deviceto energize the other I phase of said driving motor, whereby the latter rotates to actuate the rotor winding of said inductive device upon relative angular displacement of said direction responsive means in azimuth. 11. In combination, controlling means comprising an inductive device having a stator wind- 50 ing and a rotor winding, one of said windings being polyphase and the other being single-phase, a two-phase alternating current driving motor connected to actuate the rotor winding of said inductive device and having a winding in each phase, a source of periodically varyin current,

of predetermined frequency, means for producing a second periodically varying current having a frequency which is an even multiple or the frequency of said first current, means connectin one phase of said driving motor for energization by said second current, a magnetic induction device adapted to be traversed by a magnetic flux of a uni-directional magnetic field and including relatively stationary core means of magnetically permeable material having a polyphase winding winding and and a single phase winding thereon, means connecting the polyphase winding of said induction device to the polyphase winding oi. said inductive device, means connecting the single-phase winding 01 said induction device to said source of periodically'varying currentv of predetermined ing an inductive device having a multipolar stator winding and a rotor winding in inductive relation with said stator winding, a two-phase alternating current driving motor connected to actuate the rotor winding of said inductive device, a source of alternating current oi predetermined i'requncy, means for producing a second altemating current having a frequency twice that of said first alternating current, means connecting one phase oi said driving motor for energization by said second current, directionresponsive means comprising a magnetic induction device adapted to be traversed by a magnetic flux of a uni-directional magnetic field and including core means or magnetically permeable material having a multipolar output winding and an input winding thereon, means connecting the multipolar winding of said induction device to the-multipolar winding of said inductive device, means connecting the input winding 01' said induction device to said source of alternating current 01' predetermined frequency, whereby an alternating current is.generated in the multipolar output winding of said induction device having the same frequency as said second alternating current for energizing the multipolar winding of said inductive device, and means connecting the rotor winding of said inductive device motor, whereby the latter'rotate to actuate the rotor winding of said inductive'device upon relative angular movement between said induction device and said uni-directional magnetic field.

13. In combination, controlling means comprising an inductive device having a, multipolar stator a rotor winding in inductive relation with said stator winding, an electromagnetic actuating device connected to rotate the rotor windings! said inductive device, a source 01' alternating current, an induction device comprising a closed core or highly permeable magnetic material having a plurality of pole pieces projecting therefrom adapted to receive a magnetic flux from a uni-directional magnetic field, a winding said pole pieces, said pole piece windon each or ings being connected in multipolar relation to the multipolar winding 01' said inductive device,

a single phase winding on said closed core connected to be energized by said ource oi alternating current forvarying the uni-directional flux in said pole pieces whereby another alternating current is induced in" said pole piece windings, and means connectin the rotor winding of said inductive device to energize the electromagnetic actuating device, whereby the latter rotates the rotor 01' said inductive device upon relative angular movement between said induction device and said uni-directional magnetic field.

14. In combination, clmtroliing mea s comto the other phase 01' said driving prising an inductive device having a multipolar stator winding and a rotor winding in inductive relation with said stator winding, an electromagnetic actuating device connected to rotate the rotor winding of said inductive device, a source of alternating current, direction responsive means comprising an induction device including a multipolar winding connected to the multipolar winding of said inductive device and a single phase winding energized by said source oi alternating current, whereby another alternating current is generated in the multipolar winding of said induction device, and means connecting the rotor winding of said inductive device to energize the electromagnetic actuating device, whereby the latter rotates the rotor winding of said inductive device upon relative angular displacement of said direction responsive means in azimuth.

15. In combination, controlling means comprising an inductive device having a stator winding and a rotor winding, one of said windings being polyphase and the other being single phase, means comprising an electromagnetic actuating device connected to rotate the rotor winding of said inductive device, a source of periodically varying current, a magnetic induction device comprising a relatively'stationary core of permeable magnetic material adapted. to be traversed by a magnetic flux from a uni-directional magnetic field and having a polyphase winding thereon, means connecting said induction device to said source of periodically varying current to vary the reluctance of said core, whereby another periodically varying current is generated in the polyphase winding of said core member by the magnetic flux traversing said core member, means connecting the polyphase winding of said induction device to the polyphase winding of said inductive device, and means connecting the single phase winding of said inductive device to energize the electromagnetic actuating device, whereby the latter rotates the rotor winding of said induc- -tive device upon relative angular movement between the core of said induction device and said uni-directional magnetic field.

, 16. In combination, controlling means comprising an inductive device having a stator winding and a rotor winding, one or said windings being polyphase and the other being single phase,

an electromagnetic actuating device including relatively stationary coil means and a movable member cooperating with said coil means, means connecting said movable member to rotate the rotor winding of said inductive device, a source of periodically varying current, a magnetic induction device .comprising relatively stationary core means 01' permeable magnetic, material.

adapted to be traversed by a magnetic flux from a uni-directional magnetic field and having a polyphase winding thereon, means connecting said induction device to said source of periodically varying current to vary the reluctance of said core means whereby another periodically varying current is generated in the polyphase winding of said core means by 'the magnetic flux traversing said core means, means connecting the polyphase winding of said induction device to the polyphase windingof said inductive device, and means connecting the single phase winding of said inductive device to energize the coil means of said electromagnetic actuating device, whereby the latter rotates the rotor winding of said inductive device upon relative angular displacement between said induction device and said uni-directional magnetic field.

17. In combination, controlling means comprising an inductive device having a multipolar stator winding and a rotor winding, an electromagnetic actuating device, means mechanically connecting said actuating device to the rotor winding of said inductive device for rotating said rotor winding, a source of alternating current, an induction device comprising a closed'core of permeable magnetic material having a'plurality of pole pieces projecting therefrom adapted toreceive a magnetic flux from a uni-directional magnetic field, a winding on each of said pole pieces, said pole piece windings being connected in multipolar relation to the multipolar stator winding of said inductive device, a single phase winding on said closedcore connected to be energized by said source of alternating current, and means electrically connecting the rotor winding of said inductive device to said electromagnetic actuating device for energizing the latter.

18. In combination, controlling means comprising an inductive device havinga multipolar stator winding and a rotor winding, an electromagnetic actuating device, means drivably connecting said actuating device to the rotor winding of said inductive device for rotating said rotor winding, a source of alternating current, direction responsive means comprising an induction device disposed in and traversed by the magnetic flux of a uni-directional magnetic field and including a with said stationary part, means mechanically connecting said movable part to rotate the rotor of said inductive device, a source of periodically varying current, a magnetic. induction device comprising relatively stationary core means of permeable magnetic material adapted to be tra' versed by a magnetic flux from a uni-directional magnetic field and having a polyphase winding thereon, means connecting said induction device to said source of periodically varying current to vary the reluctance of said core means, whereby another periodically varying current is generated in the polyphase winding of said induction device by the magnetic flux traversing said core means, means connecting the polyphase winding of said induction device to the polyphase winding of said inductive device, and means electrically connect- 30. ing the single phase winding of saidinductive destationary multipolar winding electrically .con-

nected to the multipolar winding of said inductive device and a stationary single phasewinding electrically connected to said source of alternating vice to the coil means of said electromagnetic device for energizing the latter to actuate the movable part thereof.

ALFRED A. STUART, J a. 

